1. Field of the Invention
This invention relates to read/write head positioning mechanism for a magnetic or optical disk storage system.
2. Description of the Related Art
Conventional art 1.
FIG. 51 shows a conventional head positioning mechanism as disclosed in U.S. Pat. No. 4,630,145. A floppy disk 1 is used as a recording medium. A carriage 2 mounts a head 3. A first stepping motor 5 ("stepping motor" is abbreviated to "STM" hereinafter) has a first lead screw 4. Guide rods 6, 7 support the carriage 2 so that the carriage could slide bi-directionally as shown by arrows X1, X2. A rotor 8 is provided and combined with the first lead screw 4 to form a single unit. The first lead screw 4 and the carriage 2 are engaged. The carriage 2 can be moved bi-directionally, as shown by arrows X1, X2, by a rotation of the first lead screw 4 of the first STM 5.
A second STM 9 has a second lead screw 10. The first STM 5 and the second STM 9 are fixed to a frame 11 so that the first lead screw 4 and the second lead screw 10 could be parallel. The first bearing 12 holds the extended shaft of the first lead screw 4 at the front of the first STM 5. The first bearing 12 is able to slide bi-directionally as shown by arrows X1, X2. A second bearing 13 holds the extended shaft of the first lead screw 4 at the rear of the first STM 5. A bias spring 14 biases the first lead screw 4 to the direction as shown by arrow X1.
One end of a lever arm 15 contacts a post 16, and the other end is engaged with the second lead screw 10. The extended shaft of the first lead screw 4 penetrates the lever arm 15 in such fashion that the first lead screw 4 can rotate freely. The first lead screw 4 is located between the second lead screw 10 and the post 16. The lever arm 15 has a contact point 17, contacting the first bearing 12. The lever arm 15 pivots around the post 16 bi-directionally, as shown by arrows Q1, Q2 in FIG. 51, by a rotation of the second lead screw 10. The first bearing 12 moves bi-directionally, as shown by arrows X1, X2, when the lever arm 15 pivots bi-directionally as shown by arrows Q1, Q2. With this pivot, the first lead screw 4 moves bi-directionally as shown by arrows X1, X2.
An operation is explained hereinafter. The carriage 2 can be moved bi-directionally, as shown by arrows X1, X2, by a rotation of the first lead screw 4 of the first STM 5. In this way, the head 3 can be positioned coarsely over the floppy disk 1. And, the lever arm 15 pivots bi-directionally as shown by arrows Q1, Q2 by a rotation of the second lead screw 10 of the second STM 9. This causes the first lead screw 4 to move bi-directionally as shown by arrows X1, X2. Therefore, the carriage 2 is also moved bi-directionally, as shown by arrows X1, X2. In this way, the head 3 can be positioned finely over the floppy disk 1. By utilizing a principle of leverage, the displacement of the engaged part of the lever arm 15 with the second lead screw 10 is reduced. The lever arm 15 transmits the reduced displacement to the first lead screw 4.
Conventional art 2.
FIG. 52 illustrates "Head Moving Apparatus", described in Japanese Unexamined Patent Publication No. 52384/1988. According to this mechanism, the head 3 is moved coarsely by a rotation of the lead screw 4 of the STM 5 (STM for coarse moving). The head is moved finely by an axial movement of the lead screw 4 by the STM 9 (STM for fine moving). A motor shaft 5a of this STM 5 and the lead screw 4 of this STM 5 are formed separately, and a rotation transmission means 5b, which transmits a rotation of the STM 5 to the lead screw 4, is provided. Namely, the lead screw 4 is rotated by the STM 5 through the rotation transmission means 5b, and only the lead screw 4 is moved in its axial direction by the fine moving mechanism.